nlspace wrote: ↑
Tue Dec 24, 2019 6:17 am
Found a couple of videos but no details. Looks to me that fire started where the added wires entered the pack (sharp edges slice insulation?), oem pack did not catch
Thanks for the finds.
In the case of the first video/stills, it looks to me that the extra wires included many thin wires. So it appears that they paralleled cells so that the original BMS would protect the added cells as well as the original cells. That saves the cost of an additional BMS, but I'm guessing more importantly it avoided the need to integrate the two BMSs.
If I'm right, that's 97 thin and unfused wires with complete battery potential between the end two wires, and anything from one to 95 cells worth between any other pair of wires. It's bad enough when the manufacturer does this with short wires professionally crimped and with industrial connectors all within the sealed battery shell, but to connect all those wires to a home made battery, regardless of the quality and care involved, is just begging for trouble to me.
I actually prefer the Mitsubishi iMiev cell top BMS design, to avoid all those unfused wires altogether.
Any clues as to whether they really did have many thin wires would be appreciated.
Also @mux, does your extender pack do this, or does it have its own BMS?
[ Edit : even when the contactors are off, these wires would be live 24/7. Even with the safety disconnect out, some pairs of wires would have up to 3/4 of the pack voltage between them, since the Leaf disconnect splits the battery 3/4 and 1/4. So it's never safe. Again, all if and only if I'm right about those wires. ]
2012 Leaf with new battery May 2019. New to me June 2019.